Steerable, follow the leader device

ABSTRACT

A highly articulated robotic probe (HARP) is comprised of a first mechanism and a second mechanism, one or both of which can be steered in desired directions. Each mechanism can alternate between being rigid and limp. In limp mode the mechanism is highly flexible. When one mechanism is limp, the other is rigid. The limp mechanism is then pushed or pulled along the rigid mechanism. The limp mechanism is made rigid, thereby assuming the shape of the rigid mechanism. The rigid mechanism is made limp and the process repeats. These innovations allow the device to drive anywhere in three dimensions. The device can “remember” its previous configurations, and can go anywhere in a body or other structure (e.g. jet engine). When used in medical applications, once the device arrives at a desired location, the inner core mechanism can be removed and another functional device such as a scalpel, clamp or other tool slid through the rigid sleeve to perform. Because of the rules governing abstracts, this abstract should not be used to construe the claims.

The present application claims the benefit of U.S. application Ser. No.60/583,094 entitled Flexible Steerable Go-Anywhere Medical Snake Robotfiled Jun. 25, 2004, the entirety of which is hereby incorporated byreference and PCT Application No. PCT/US2005/022442 entitled Steerable,Follow the Leader Device filed on Jun. 24, 2005.

BACKGROUND

The present disclosure is an outgrowth from the field of robotics forthe field of teleoperated mechanisms and, more particularly, to threedimensional, flexible, steerable devices.

Although there are many applications for this disclosed device, themotivating application for this device is minimally invasive surgery.There are few medical robotic systems available in the market today.These systems can be categorized into three major groups: active,semi-active, and passive robotic system. The active robotic systemapproach is represented by Kazanzides et al. [Kazanzides P, MittelstadtB. Musits B, Barger W, Zuhars J, Williamson B, Cain P and Carbone E: Anintegrated system for cementless hip replacement. IEEE Engineering inMedicine and Biology. pp. 307-313, 1995] and Brandt et al. [Brandt G,Radermacher K, Lavalle S, Staudte H. W, Rau G, “A Compact Robot forImage Guided Orthopedic Surgery: Concept and Preliminary Results”,Lecture notes in Computer Science 1205, CVRMed-MRCAS '97, Troccaz J.Grimson R, and Mosges R, eds, pp. 767-776, 1997] where, in the firstexample, a serial robot actively mills the femur to optimally fit animplant for a knee surgery. This robot is a serial-type mechanism with alarge work volume relative to the task at hand. Therefore, such robotsare somewhat cumbersome and heavy, and suffer several known drawbacksincluding relatively low stiffness and accuracy, and low nominalload/weight ratio. The fact that these robots are used for medicalprocedures, where accuracy and safety are paramount, has motivatedresearchers to look for manipulators with better kinematics and dynamicperformance for specific surgical tasks.

In the second example, a Stewart platform is used in hip replacementsurgery. A Stewart platform is a type of parallel robot. A six degree offreedom parallel robot is composed of two rigid platforms, one used as abase platform and the other as a moving end-effecter. The two platformsare connected by ball-and socket joints to six links capable of changingtheir length. By controlling the length of each link, the mechanism canposition and orient the moving end-effecter relative to the baseplatform. Advantages of parallel robotic structures include: low weight,compact structure, high accuracy, high stiffness, restricted workspace,high frequency response, and low cost. [Merlet J.-P., Les RobotsParalleles, Hermes, Paris, 1997]. Moreover, parallel robots aresignificantly more robust to failure than serial devices because in aserial device, one failure can cause the robot to dramatically move,whereas in a parallel structure, one failure will have little effect onthe overall motion of the robot. This is important in medicalapplications because surgeons want the device to maintain its lastposition in case of a catastrophic failure. [Khodabandehloo K., Brett P.N., Buckingham R. O., “Special-Purpose Actuators and Architectures forSurgery Robots”, Computer Integrated Surgery, Taylor R., Lavalle S.,Burdea G., Ralph Mosges, eds, pp. 263-274, 1996].

From a robotics perspective, the main drawback of parallel mechanisms istheir limited workspace. However, as pointed out by Khodabandehloo etal., limited workspace is an advantage in medical applications becausethe active in-situ operation volumes are limited to protect the patientand physician. Unfortunately, this advantage forces the robot to bedeployed near the operation site in the operating room, which is oftenunrealistic because the robot would interfere with the surgeons. One ofthe solutions introduced to solve this problem is to attach the entirerobotic system to the operating room's ceiling so that the robot works“upside down.” [Lueth T., Bier J., “Robot Assisted Intervention inSurgery”, Gilsbach J. M. and Stiel H. S. (Editors),Neuronavigation-Neurosurgical and Computer Scientific Aspects,Springer-Verlag, Wien. 1999]. In this way, the robot does not interfereduring the standard operating procedure, and is activated and maneuveredto the operating area when required. However, this solution is notapplicable in all operating rooms and requires special operating roomdesign.

The first known robot introduced to the operating room was the Robodoc™system (Integrated Surgical Systems, Sacramento, Calif.). This robot isused to bore the medullary cavity of the femur for cementless femoralprostheses. Other robotic systems introduced in the market are the URS™,for positioning an endoscope in a tremor free and more precise way, i.e.with an accuracy of up to 1/100 mm. EndoAssist™, used for camerasupport, EndoWrist™, used for instrument support, CASPAR™, used for hipreplacement, AESOP™, used for camera support, and ZEUS™, for instrumentsupport. Other available medical robotic systems are the Neuromate™,used for endoscope/catheter guidance, the MKM™, used for microscopesupport, and the SurgiScope™, also used for microscope support.

The semi-active robotic system approach is represented by Ho et al. [HoS C, Hibberd R D, Davies B L, “Robot Assisted Knee Surgery”, IEEEEngineering in Medicine and Biology, Vol. 14, pp. 292-299, May/June1995], Kienzle et al. [Kienzle III, T, Stullberg D., Peshkin M., QuaidA., Lea J., Goswami A., Wu Ch., “A Computer-Assisted Total KneeReplacement Surgical System Using a Calibrated Robot”, In Computerintegrated surgery. Tatlor, Lavallee, Burdea, and Mosges, eds, MITPress, pp. 410-416, 1996], and Harris et al. [Harris S J., Lin W J, FanK L, Hibberd R D, Cobb J, Middelton R, Davies B L, “Experiences withRobotic Systems for Knee Surgery”, Lecture notes in computer science1205, CVRMed-MRCASD '97]. In Kienzle et al. the robot acts as anassistant during the operation by holding a tool in a steady position,accurately guiding a cutting tool, and preventing the tool from movingout of the desired operative region. A third approach, passive roboticsystems, is represented by Grace et al. [Grace K. W., Colgate J. E.,Gluksberg M. R., Chun J. H., “Six Degree of Freedom Micromanipulator forOphthalmic Surgery”, IEEE International Conference on Robotics andAutomation, pp. 630-635, 1993], and Jensen et al. [Jensen P. S.,Glucksberg M. R., Colgate J. E., Grace K. W., Attariwala R., “RoboticMicromanipulator for Orthopedic Surgery”, 1^(st) International Symposiumon Medical Robotics and Computer Assisted Surgery, pp. 204-210,Pittsburgh 22-24, 1994], where a six degree of freedom robot acts simplyas a guided tool, fully controlled by the surgeon.

The third category of medical robots is the passive system. This kind ofrobotic system supports the surgical procedure, but takes no active partduring surgery, in other words: the surgeon is in full control of thesurgical procedure at all times. There are also few robotic systemswhich fall in this category. Matsen et. al. [Matsen F A III, Garbini JL, Sidles J A, Prat B, Baumgarten D, Kaiura R, Robotic assistance inOrthopedic surgery, Clin Orthp and Rela Res 296, 1993: 178-186.] reporton a passive robotic system for knee arthroplasty. For their researchthey use a commercial Unimation PUMA 260, who hold a three dimensionaltransparent template which enables the surgeon to indicate the desiredposition of the prosthetic joint surface. The robot then places the sawguide such that the resulting cut plane agrees with the one indicated bythe surgeon, who is actually the one holding the power saw andperforming the cuts. This system was never used in the operating room.

McEwen et. al. [McEwen C, Bussani C R, Auchinleck G F, Breault M J.Development and initial clinical evaluation of pre robotic and roboticretraction systems for surgery. 2^(nd) Annual Int Symposium CustomOrthopaedic Prosthetics, Chicago, October 1989.] use Arthrobot as anassistant in the operating room. The robot is neumatically powered,electronically controlled positioner device which is usedintraoperatively to hold the limb. The system has no sensingcapabilities and is able to move only under explicit human control. Thesystem was used during arthroplasties of the knee and hip.

Other passive robotic systems are reported by Grace et. al. [Grace K.W., Colgate J. E., Gluksberg M. R., Chun J. H. A Six Degree of FreedomMicromanipulator for Ophthalmic Surgery. IEEE International Conferenceon Robotics and Automation 1993; 630-635.] yet these are not related toorthopedic applications. Grace developed a six degrees of freedom micromanipulator which is used for treatment of retinal venous occlusion.During procedure, the operator is watching the robot's end-effector(using a microscop) and guiding it using a multi-dimensional joystickinput device.

However, the most frequent examples of passive robotic systems aresurgical navigation systems, as they represent the central element ineach CAOS system [Nolte L P, Langlotz F, Basics of computer assistedorthopedic surgery (CAOS), Navigation and robotics in total joint andspine surgery, New York, Springer, 2004.] Basically, a navigation systemrefers the position i.e. location and orientation, of the actingcomponents of the system to a global coordinate system, such that theirrelative position can be resolved in the global system.

The inventors of the current patent application have built many othertypes of robots. One of their specialties includes snake robots,formally called hyper redundant mechanisms. Snake robots can be used inan active, semi-active, and passive manner. The snake robot was designedand constructed originally to assist in search and rescue tasks. [Wolf,A, Brown, H. B., Casciola, R., Costa, A., Schwerin, M., Shamas, E.,Choset, H., “A mobile hyper redundant mechanism for search and rescuetasks”, Proceedings of IEEE/RSJ IROS2003]. The construction of thisrobot required a new mechanical design such that the robot would bestiff enough to support its own mass while consuming a minimum of powerand volume. The new joints in this robot, designed and constructedin-house, have a large range of motion suitable for a hyper-redundantsnake. [Shammas, E., Wolf, A., Brown, H. B., Choset, H., “New JointDesign for Three-dimensional Hyper Redundant Robots”, Proceedings ofIEEE/RSJ IROS2003]. The snake robot was attached on top of a mobileplatform so that the snake could be semi-autonomously transported to thesearch area. Control of the mobile robot platform and the snake robot isperformed through a joystick, to provide the user with a simple,intuitive interface. Snake robot control is performed within thereference frame of the camera, such that inputs from the joystick areconverted into the camera reference frame. [Wolf, A, Choset, H., Brown,H. B., Casciola, R., “Design and Control of a Hyper-RedundantMechanism”, Submitted to IEEE Transactions on Robotics]. If this type ofdevice can be built With a reduced cross-sectional diameter, then thistype of snake robot can also be used to allow surgeons to reach areas ofthe body in a minimally invasive fashion and to perform operations withtools at the tip of the snake robot.

Virtually all previous work in hyper redundant robots focused on themechanism development and end effecter placement. [Chirikjian G., S.,Burdick W., J., (1995a) Kinematically optimal hyper-redundantmanipulator configurations, IEEE Tran. On Rob and Aut, 11 (6), pp.794-806] [Chirikjian G., S., Burdick W., J. (1995b) The kinematic ofhyper-redundant robot locomotion, IEEE Tran. On Rob and Aut, 11(6), pp.781-793] Most of these devices were limited to the large scale.Historically, Hirose, in 1972, developed an impressive device thatmimicked the locomotion of real snakes on the ground [Hirose, S.Biologically Inspired Robots: Snake-like Locomotors and Manipulators.Oxford University Press Oxford 1993]. Research continued in the early1990's at Caltech with the planar hyper-redundant manipulator byChirikjian and Burdick; their contribution focused on novel end effecterplacement algorithms for these robots, not the robot itself (Chirikjianand Burdick, 1995). Recently, other researchers, such as Yim at XeroxParc, Miller on his own and Haith at NASA Ames, have duplicated Hirose'spioneering work on snake locomotion, where Yim and Haith used Yim'spolybot modules to form modular hyper-redundant mechanisms. Modularityclearly has its benefits, but comes at an unacceptable cost, whichmanifests itself in a loss of strength and maneuverability. Theelectro-mechanical connection is polybot's innovation, but it alsoprovides a point of weakness to the mechanism and it occupies space thatmakes the robot more discrete (increase in link length, i.e., separationin degrees of freedom (DOF)) and hence reduces maneuverability.Modularity has more value when the target configuration of the robot isunknown a priori.

The challenge of a hyper redundant mechanism is to be strong enough tolift itself in three dimensions but be small and light enough to beuseful to even demonstrate basic planning. The Pacific Northwest Labsdeveloped a three-dimensional mechanism which was incredibly strong butmoved too slowly and was too large. This robot moved too slowly becauseit was intended to be used for bomb disarming, so that a techniciancould tele-operate this robot to probe the internals of a bomb withoutaccidentally detonating it. Kinematically, the mechanism is a sequenceof linearly actuated universal joints stacked on top of each other.Takanashi developed at NEC a new two-DOF joint for snake robots thatallowed a more compact design. This joint used a passive universal jointto prevent adjacent bays from twisting while at the same time allowingtwo degrees of freedom: bending and orienting. This universal jointenveloped an angular swivel joint, which provided the two degrees offreedom. The universal joint being installed on the outside rendered thejoint too bulky. Researchers at Jet Propulsion Laboratory (JPL)“inverted” Takanashi's design by placing a small universal joint in theinterior of the robot. This allowed for a more compact design, but cameat the cost of strength and stiffness (backlash). A small universaljoint cannot transmit rotational motion at big deflection angles nor canit withstand heavy loads.

For certain applications it is desired that the hyper redundant robotoperate on the size of less than 15 mm diameter that is normallyrequired for minimally invasive surgery. The many degrees ofarticulation that furnish the hyper redundant robot with its enhancedcapabilities also offer its main research challenges. There are severalcritical challenges that one must address to build a hyper redundantrobot. First, there is the actual mechanical design itself; constructinga device that has high maneuverability in a small confined volume. Lowlevel control is another challenge in such small scales. The compactspace inside the device envelop leaves little room for wiring allactuators and sensors on board the hyper redundant robot, hence a moreadvanced low level controller should be used.

One avenue of research to reduce the size of hyper redundant robots hasfocused on exotic actuator development such as shape memory alloys.Numerous works have been presented on active catheters and endoscopes,most actuated by shape memory alloys (SMA) actuators (Tohuko University,Olympus Optical Co). SMA spring and wire actuation has been implementedby Hirose [Hirose, S. Biologically Inspired Robots: Snake-likeLocomotors and Manipulators. Oxford University Press Oxford 1993] toovercome hysteresis problem of the SMA material. The Santa Annalaboratory in Pisa Italy (Dario et. al 2000), developed an arthroscopetool which is cable actuated; a position sensor detects the tip locationand a force sensor detects contact forces. Overall accuracy of thedevice is 2.3 mm. Other endoscope like active mechanisms are theLaboratorie de Robotque de Paris (LRP), 8 mm in diameter worm likemechanism which is formed by a sequence of segments articulated to eachother by SMA actuated pin joints [Kuhl C., Dumont G., Virtual endoscopy:from simulation to optimization of an active endoscope. Proc. Of themodeling & simulation for computer aided medicine and surgery 2002, 12,pp 84-93]. The device is specifically designed to explore the intestinewith a camera. An electrostrictive polymer artificial muscle (EPAM)based snake like endoscopic robot was developed at Stanford ResearchInstitute (SRI). That device is composed of several blocks joined by aconcentric spine [Kombluh R D., Pelrine R., Eckerle J., Joseph J.,Electrostrictive polymer artificial muscle actuators. Proc. Of the IEEEint. Conf. on Robotics and Automation 1998, pp 2147-2154]. Researchersat Pennsylvania state university [Frecker M I., Aguilera W M.,Analytical modeling of a segmented unimorph actuator using electroactive(pvdf-trfe) copolymer. Smart material and structures 2003, pp 82-91]have also developed a snake like manipulator using electrostrictivepolymer artificial muscle. Their special design of the actuator allowscontrol of the curvature.

As an alternative to an articulated probe, researchers have considered amobile type of robot that resembles a miniature inch worm for both pipeinspection and medical procedures. Several manuscripts have beenpublished regarding miniature inchworm-like mechanisms which are capableof maneuvering within rigid-pipes. The Kato device [Kato S., HirayamaT., Fabrication of a high speed in-pipe mobile micro machine. Proc. ofthe 4^(th) Japan-France Congress and 2^(nd) Japan-Europe congress onMechatronics, 1998, 1, pp 429-432] is a 96 mm long, 18 mm in diametermechanism which is capable of moving inside tubes using stick and slipstrategy. This mechanism is not designed to move itself within adeformable environment (intestine). The walking work by Sanata AnnaUniversity is a 90 mm long, 18 mm in diameter SMA based worm likemanipulator which clamps itself into the environment and thenmanipulates itself forward [Dario P., Menciassi A., Park J H., Lee L.,Gorinil S., Park J., Robotic solutions and mechanisms for asemi-automated endoscope. Proc. of the IEEE/RSJ international conf. onrobotic systems, 2002, p. 1379-1384.

Focusing now on basic research specific to medical articulated probes,in Geunbae L., Kazuyuki M., Keisuke Y., Masahisa S., et. al (1996)Multi-link active catheter snake-like robot, Robotica, 14, pp. 499-506,the researchers developed a 2.8 mm diameter active catheter based onsilicon micromachining. This multilane manipulator is connected byjoints made of shape memory actuators (SMA), fixed at equilateraltriangular locations to allow bending in several directions. In thisdesign an indirect heating was developed due to the SMA when the controlsystem was integrated into the manipulator. Other endoscopic, SMA based,tools are presented in [Nakamura Y., Matsui A., Saito T., Yoshimoto K.,(1995) Shape-memory-alloys active forceps for laparoscopic surgery, IEEEint. Cof. on Robotics ad Automation, pp. 2320-2327]; [Ikuta K.,Tsukamoto M., Hirose S., (1988) Shape memory alloys servo actuatorsystem with electric resistance feedback and application for activeendoscope, Proc. of IEEE Int. Conf. Rob. And Aut. pp. 427-430]; [IkutaK, Nolata M., Aritomi S., (1994a) Hyper redundant active endoscope forminimally invasive surgery, Proc. Of the first symposium on medicalrobotics and computer assisted surgery, Pittsburgh, Pa., pp. 230-237];[Ikuta K., Nokata M., Aritomi S., (1994b) Biomedical micro robot drivenby miniature cybernetic actuator, IEEE Int. Workshop on MEMS, pp.263-268]; [Dario P., Carrozza M. C.; Lencioni L., Magnani B., et. al,(1997a) A micro robotic system for colonoscopy, Proc. Int. Conf Rob. andAut. pp. 1567-1572]; [Reynaerts D., Peirs J., Van Brussel H., (1999)Shape memory micro-actuation for a gastro intestinal interventionsystem. Sensor and actuators, 77, pp. 157-166]. However, those toolshave relatively low stiffness, and they require high activation voltage.Hence, heat removal becomes a challenge. A different activation conceptis presented in [Piers J., Reynaerts H., Van Brussel H., De Gersem G.,(2003) Design of and advanced tool guiding system for robotic surgery,IEEE Int. Conf. Rob and Aut, pp. 2651-2656]. In that work, the authorspresented a 5 mm diameter wire driven two degrees of freedom snake robottool using super-elastic NiTi [Simaan N., Taylor R., and Flint P.,(2004) A Dextrous System for Laryngeal Surgery: Multi-Backbone BendingSnake-Like Robot for Dexterous Surgical Tool Manipulation. IEEETransaction of ICRA 2004, New Orleans]. Other devices are reported inReynaerts. D., Peiers L., Van Brussel H., Design of a shape memoryactuated gastrointestine intervention system. Proc. of the int. C of. ofnew actuation 1997, Epacenet mechanism and Young M L., Jinhee L., JisangP., Byugkyu K., Jong Oh P., Soo Hyun K., Yeh-Sun H., Self propellingendoscopic system. Proc. of the 2001 IEEE/RSJ Int. Conf. on intelligentrobotic systems. 2002, pp 117-1122. However, wire actuation, SMA, andEPAM actuation become challenges with robots having multiple degrees offreedom due to minimal space inside the robot's mechanical envelope.Therefore, most of these systems were developed to be introduced into aconfined tube-like environment or work as bending mechanisms not capableof generating a 3D curve (e.g. double non-planar “S” shape).

Robert Sturges' U.S. Pat. No. 5,759,151, which is hereby incorporated byreference in its entirety, discloses a flexible, steerable device forconducting exploratory procedures. The device includes at least onespine, each having stiffening means for selectively rendering the spinerigid and flexible along its length. A flexible sheath surrounds thespine and is axially slidably moveable relative to the spine so that thesheath will follow and conform to the shape of a spine in the rigidstate and resist further flexure when the spine is in a relaxed state. Asteerable distal tip is provided on the distal end of the device.Controls for the distal tip are mounted on the proximal end of thedevice. Mechanisms are provided on the distal end of the device forselectively activating and deactivating the stiffening means of thespine. An instrument conduit may be mounted on the sheath.

U.S. Pat. No. 6,610,007 discloses a steerable endoscope having anelongated body with a selectively steerable distal portion and anautomatically controlled proximal portion. The endoscope body isinserted into a patient and the selectively steerable distal portion isused to select a desired path within the patient's body. When theendoscope body is advanced, an electronic motion controller operates theautomatically controlled proximal portion to assume the selected curveof the selectively steerable distal portion. Another desired path isselected with the selectively steerable distal portion and the endoscopebody is advanced again. As the endoscope body is further advanced, theselected curves propagate proximally along the endoscope body, and whenthe endoscope body is withdrawn proximally, the selected curvespropagate distally along the endoscope body. This creates a serpentinemotion in the endoscope body allowing it to negotiate tortuous curvesalong a desired path through or around and between organs within thebody.

SUMMARY OF THE PRESENT DISCLOSURE

A steerable, follow the leader device is disclosed which is capable ofsteering anywhere in three dimensions, such as, but not limited to,cluttered intracavity spaces, as well as the inside of a natural pathwaysuch as a pipe, tube, intestines, or blood vessels, to name a few. Thedevice is comprised of a first mechanism having a plurality of links anda first locking device for enabling the first mechanism to have a rigidstate and a limp state. A second mechanism is comprised of a pluralityof links and a second locking device enabling the second mechanism tohave a rigid state and a limp state, and wherein at least one of thefirst and second mechanisms, or both, are steerable. In this embodiment,the first and second mechanisms may be positioned side by side or onewithin the other.

Another embodiment of the present disclosure is directed to a highlyarticulated probe comprising an inner core having a plurality of linksand an outer sleeve having a plurality of links. A first wire extendsthrough either the plurality of links of the inner core or the pluralityof links of the outer sleeve and a plurality of wires runs through theother of the plurality of links of the inner core or the plurality oflinks of the outer sleeve. A device produces command signals. Anelectromechanical feeder is responsive to the command signals foralternating each of the inner core and the outer sleeve between a limpmode and a rigid mode and for advancing and retracting the inner coreand the outer sleeve. In this embodiment, at least one of the inner coreor the outer sleeve, or both, are steerable.

According to an embodiment of the present disclosure, a method ofoperating a follow the leader type of device is comprised of controllingthe states of a first mechanism and a second mechanism such that onemechanism is rigid and one mechanism is limp, advancing the limpmechanism a predetermined distance, changing the states of themechanisms, and repeating the advancing and changing until the device ispositioned as desired. In this method, steering may be accomplished bysteering the first mechanism while it is limp, or steering the secondmechanism while it is limp, or by steering both mechanisms when they arelimp.

According to another embodiment of the present disclosure, a method ofmoving a steerable, follow the leader device in a three dimensionalspace is comprised of generating images from a device mounted on the endof the steerable, follow the leader device. The steerable follow theleader device can be constructed according to any of the embodimentsdiscussed above. The images are used to control the movement of thefollow the leader device. The device mounted on the end of the followthe leader device includes one of a camera or a lens and light pipe. Themethod can be carried out in real time. When the space is thepericardium, the method additionally comprises making an incision belowthe xiphoid process and inserting the steerable, follow the leaderdevice into the incision.

BRIEF DESCRIPTION OF TEM DRAWINGS

For the present disclosure to be easily understood and readilypracticed, various embodiments of the present disclosure will now bedescribed, for purposes of illustration and not limitation, inconjunction with the following figures wherein:

FIGS. 1A-1C are graphic demonstrations of the concept of the presentdisclosure;

FIGS. 2A-2D illustrate various configurations assumed by a prototype ofone embodiment of the disclosed device;

FIGS. 3A-3D illustrate various views of a cylinder of the outer sleeve;

FIGS. 4A and 4B illustrate end and cross-sectional views, respectively,of a cylinder of the inner core;

FIGS. 5A-5D illustrate various views of another embodiment of a cylinderof a steerable inner core;

FIGS. 6A and 6B illustrates one example of a feeder mechanism;

FIG. 7 illustrates devices for controlling the tension on the wires;

FIG. 8 illustrates devices for controlling the tension on the wires ofthe outer sleeve;

FIG. 9 illustrates a device for controlling the tension on the wire ofthe inner sleeve;

FIGS. 10A-10C illustrate a schematic of extreme cantilever configurationfor a worst case configuration (A), a simplified model (B), and a freebody diagram (C) for the worst case configuration;

FIG. 11 is a block diagram illustrating the components of a controlsystem and the flow of information between those components;

FIG. 12 is a block diagram of an exemplary electrical system for thefeeding mechanism;

FIGS. 13A, 13B and 13C are an electrical schematic of a PID motorcontroller of FIG. 12;

FIG. 14 is flow chart of a stepped advancing mode of operation;

FIGS. 15A-15C illustrate a process for moving the device of the presentdisclosure;

FIG. 16 is a flow chart of a process for retracting the device;

FIG. 17 illustrates another embodiment of a link which may be used inthe device of the present disclosure;

FIGS. 18 and 19 illustrate an embodiment of the present disclosurehaving an onboard camera mounted on the end thereof and used forvisualization of internal organs; and

FIG. 20 illustrates another embodiment of the device of the presentdisclosure.

DESCRIPTION

A highly articulated robotic probe (HARP) 10 of one embodiment of thepresent disclosure shown in FIGS. 1A-1C is essentially two concentricmechanisms, an outer one and an inner one, each of which can be viewedas a steerable mechanism. FIGS. 1A-1C show the concept of how differentembodiments of the HARP 10 operate. Referring to FIG. 1A, we call theinner mechanism a first mechanism or inner core mechanism 12. We callthe outer mechanism a second mechanism or sleeve mechanism 14. Eachmechanism can alternate between being rigid and limp. In the rigid modeor state, the mechanism is just that—rigid. In the limp mode or state,the mechanism is highly flexible and thus either assumes the shape ofits surroundings or can be reshaped. It should be noted that the term“limp” as used herein does not denote a structure that passively assumesa particular configuration dependent upon gravity and the shape of itsenvironment; rather, the “limp” structures described in this applicationare capable of assuming positions and configurations that are desired bythe operator of the device, and therefore are articulated and controlledrather than flaccid and passive.

With this HARP 10, one mechanism starts limp and the other starts rigid.For the sake of explanation, assume the sleeve 14 is rigid and the core12 is limp, as seen in step 1 in FIG. 1A. Now, the core 12 is bothpushed forward by a feeding mechanism 16, described below, and its“head” or distal end is steered, as seen in step 2 in FIG. 1A. Now, thecore 12 is made rigid and the sleeve 14 is made limp. The sleeve 14 isthen pushed forward until it catches up or is coextensive with the core12, as seen in step 3 in FIG. 1A. Now, the sleeve 14 is made rigid, thecore 12 limp, and the procedure then procedure repeats. One variation ofthis approach is to have the sleeve 14 be steerable as well. Theoperation of such a device is illustrated in FIG. 1B. In FIG. 1B it isseen that each mechanism is capable of catching up to the other and thenadvancing one link beyond. That requires an additional camera on thesleeve 14 but would potentially allow for quicker deployment of the HARP10. In the current rendition, the sleeve 14 is steerable and the core 12is not. The operation of such a device is shown in FIG. 1C.

In medical applications, once the HARP 10 arrives at a desired location,the surgeon can remove the inner core 12 and slide either a conventionaldevice or a custom tool through the rigid sleeve 14 to perform variousoperations.

The HARP 10 is not limited to surgery, but can be used in engineinspection, engine repairs, and engine retrofitting. Other applicationsinclude tank inspection, spying or surveillance applications, bombdisarming, and inspection or repairs in tightly confined spaces such assubmarines or within nuclear weapons. Other applications includestructural (e.g. building) inspections, hazardous waste remediation andbioterrorists sample recovery. Clearly, the device of the presentdisclosure has a wide variety of applications and should not be taken asbeing limited to any particular application.

The HARP 10 of the present disclosure device bears some similarities toBob Sturges' patented device (U.S. Pat. No. 5,759,151) although thepresent disclosure incorporates several major innovations. First, thecore 12 and/or sleeve 14 is steerable. Second, the sleeve 14 can be madeboth rigid and limp. These two innovations allow the HARP 10 to driveanywhere in three-dimensions. Sturges' device assumes that it is movingthrough a tubular space, such as the large intestines. Sturges' devicerequires that the intestines shape the device as it goes. As Sturges'device propagates out it, cannot “remember” its previous configurationand hence cannot keep the path it followed due to the fact that it iscomposed of only one element that can become both rigid and stiff. TheHARP 10 can “remember” its previous configurations and for this reason,the HARP 10 can go anywhere in a three dimensional volume such as theintracavity spaces in a body. FIGS. 2A-2D illustrate variousconfigurations assumed by a prototype of the device 10.

The following discussion contains details of a preferred embodiment. Thereader should recognize that the present disclosure is not to be limitedby the detailed information that follows. Rather, the detailedinformation is intended for purposes of illustration and not limitation.As can be seen in FIGS. 3A-3D and 4A and 4B the sleeve 14 and core 12,respectively, are made up in this embodiment of concentric cylinders 22,24, respectively, although links of other shapes may be used, e.g. adogbone configuration (not shown) as well as links of a type that arenot concentric, e.g. backbone configuration (see FIG. 17), among others.The ends of the cylinders 22, 24 are not flat but instead one end 26 isan “outer” or convex hemisphere and the other end 28 is an “inner” orconcave hemisphere, both with the same radius of curvature R. Thecylinders 22, or links, of the outer sleeve 14 are “chained”back-to-back such that the concave end 28 of one mates with the convexend 26 of an adjacent cylinder. Similarly, the cylinders 24, or links,of the inner core 12 are chained back-to-back. The result is aspherical-like joint, from a kinematic point of view. In the currentembodiment, each link is able to rotate on the adjacent link's head,acting as a spherical joint with approximately 14° range of motion inany direction, although other ranges of motion are possible. Thecylinders 22 have three channels 30 extending therethrough for controlwires.

FIGS. 5A and 5B illustrate another embodiment in which the core 14 issteerable. The core 14 of this embodiment is comprised of cylinders 24′which have a convex 26 and concave 28 end. However, the cylinders 24′have three channels 32 for control wires.

The heads (i.e. the distal cylinders) of both the sleeve 14 and the core12 are steerable using three cables which are attached at, for example,120° from each other. As can be seen in FIGS. 3A-3D and FIGS. 5A-5D,there are three small cylindrical channels 30, 32, respectively, forwires to pass through. In the version of the device shown in FIGS. 4Aand 4B, the inner cylinder 24 has only one wire, in which case there isonly one hole 34 through its center.

It will be appreciated that although the preferred embodiment describedabove utilizes cables or wires, alternative means of manipulating thelimp elements, such as miniature pneumatic or hydraulic cylinders orother mechanical linkages situated between individual links, can beemployed without falling outside the scope of this invention.

The links, and hence the HARP 10, can be made out of virtually anymaterial, including plastic, which allows it to be used online with NMR.One current prototype of our device has an outer diameter of the outersleeve 14 of 12 mm and an outer diameter of the inner core 12 of 6 mm.The choice of 12 mm is based on available port sizes. Each link of theouter sleeve 14 weighs 1.5 grams and each link of the inner core 12weighs 0.5 grams. Currently, the number of links in each of the innercore 12 and outer sleeve 14 is seventeen. Therefore, the total weight ofthe device 10 is thirty-four grams and its total length is 300 mm. Thesedimensions are intended for purposes of illustration and not limitation.

As noted, the core 12 and sleeve 14 can be made rigid or limp usingwires or cables. Although there are many variations, in the currentprototype the outer sleeve 14 consists of a set of cylinders 22 strungon three wires. The three wires are 120° apart, making it possible tosteer in any direction. This design provides a radius of curvature ofapproximately eight centimeters. When the wires are pulled towards theback of the sleeve 14, the cylinders 22 are pulled towards each other.When the pulling force increases, the friction force between adjacentcylinders 22 increases until the whole outer sleeve 14 stiffens (i.e.enters the rigid mode). When the pulling force is released, the outersleeve 14 becomes limp. Thus, the wires together with their respectivemotors form a locking device. The motors, along with the electronics forcontrolling the motors, form a means for controlling the tension on thewire. When the outer sleeve 14 is positioned one cylinder in front ofthe inner core 12, and the inner core 12 is stiff, the distal link ofthe outer sleeve 14 can be oriented by pulling one or more of the threewires. The magnitude of the pulling force which is exerted on each wirecan be controlled. By pulling the three wires with the same magnitude,the outer sleeve 14 becomes stiff without changing its shape.

The inner core 12, like the outer sleeve 14, consists of a set ofcylinders. In contrast to the outer sleeve 14, the inner core 12 doesnot need (but may optionally have) a steering ability. The inner core 12does need the ability to change from rigid mode, to limp mode, and back.Therefore, in embodiments where the inner core 12 need not be steerable,the links of the inner core 12 may be strung on a single wire, whichenables a small diameter for the device 10.

One type of feeding mechanism 16, shown in FIGS. 6A and 6B, inserts andretracts the HARP 10 into and out of, respectively, a region ofinterest. The feeder 16 has two movable carts. A first cart 42, carriedin a first fixed tray 43, drives the outer sleeve 14 while a second cart44 carried in a second fixed tray 45 drives the inner core 12. Each cart42, 44, and hence each of the inner core 12 and outer sleeve 14, isdriven independently by separate linear actuators 46, 48 respectively.The linear actuators 46, 48 may carry shaft encoders (not shown) usedfor position control as is known.

Each of the carts 42, 44 carries one or more motors necessary forcontrolling the wires of the inner core 12 and outer sleeve 14. Forexample, as seen in FIG. 7 and FIG. 8, the cart 42 carries motors 50,51, 52 which control the tension on wires 54, 55, 56 of outer sleeve 14.As shown in FIG. 9, second cart 44 has a motor 58 for controlling thetension on wire 59 of the inner core 12. Each of the motors 50, 51, 52and 58 may be provided with shaft encoders (not shown) used for positioncontrol as is known. If the inner core 12 were to also be steerable, ittoo would require three motors.

For the 12 mm diameter HARP 10, the feeder's 16 dimensions are 400 mm(long) by 100 mm (width/height), while the HARP is 300 mm long. The 12mm prototype HARP 10 is inserted into a protective plastic bag toachieve sterility. However, the device can be constructed out ofinexpensive ABS plastic rendering the device disposable.

We selected motors to handle the “worst case” configuration for thedevice, i.e. when the motors tensioning the wires have to exert the mosttorque. The “worst case” configuration is when the HARP 10 is stretchedout in a cantilever position, the outer sleeve 14 is limp, and the innercore 12 supports its own weight as well as the weight of the outersleeve 14.

To estimate the axial force needed to be applied by the wire 59 of theinner core 12 to support this configuration, we use a simplified modelof this extreme configuration. The simplified model is shown in FIGS.10A-10C where we approximate the system parameters as follows: outersleeve cylinder weight as 1.5 grams, inner sleeve cylinder weight as 0.5grams, and the number of cylinders in each is seventeen. Therefore, thetotal weight of the device is thirty-four grams and its total length is300 mm. Finally, the outer diameter of the outer sleeve 14 is 12 mm andthe outer diameter of the inner core 12 is 6 mm. The choice of 12 mm isbased on available ports and the 6 mm follows by design.

The weight of the device is simplified to a point mass at the center ofgravity of the device, The largest torque is exerted on the area betweenthe two proximal cylinders of the HARP 10. Therefore we developed asimplified model to include only one long cylinder that is in contactwith the proximal cylinder. The wire of the inner core is applied withan axial force, F, at the center of the HARP 10. A free body diagram ofthe simplified model is shown in FIG. 10C.

The approximated relation between the force F and the torque τ appliedon a circular surface with radius r and friction coefficient μ is shownin equation (1).

$\begin{matrix}{\tau = {\left. {\mu \cdot F \cdot r}\Rightarrow F \right. = {\frac{\tau}{\mu \cdot r} = {\frac{50\mspace{14mu}{N \cdot {mm}}}{{\mu \cdot 3}\mspace{14mu}{mm}} \approx \frac{17\mspace{14mu} N}{\mu}}}}} & (1)\end{matrix}$It is clear from equation (1) that the friction coefficient is animportant design criteria. When the friction between cylinders is low,the pulling force that is needed to withstand the mechanism's own weightis enormous. To find the accurate friction coefficient between cylinderssome empirical tests were needed.

Three different materials were tested: Aluminum T6061-T6, Garolite®G11/FR5 and Garolite® G10/FR4. The aluminum and Garolite® G11/FR5 had afriction coefficient of approximately 0.2-0.3, but after a few minutesof being rotated under load, the contact surface was polished andsmoothed out, and the friction coefficient dropped dramatically makingthese materials unfit for our design. The Garolite® G10/FR4, which is ahigh pressure laminated glass reinforced epoxy, has a very high frictioncoefficient (approximately 0.5) and was durable to polishing. Thismaterial is also MRI compatible.

Based on these tests, we decided to use the Garolite® G10/FR4. Thismaterial enabled the use of reasonable pulling force of the wire(approximately 35-40 N) to hold the weight of the entire device in theextreme configuration described above. Furthermore, this pulling forcewas sufficient to withstand additional torques caused by steering thedistal link of the outer sleeve.

An implication of using the Garolite® G10/FR4 was the need for anon-abrasive wire. Therefore we used the Spectra® polyethylene fiberwire, with 0.030″ diameter, a breaking force of 150 lbf, and a lowstretch (about 3%). An additional advantage of the Spectra® wire is itsvery tight radius curvature that enabled the use of a small diameterpulley (4 mm diameter) making it possible to achieve a high pullingforce per torque.

FIG. 11 is a block diagram illustrating the components of a controlsystem and the flow of information between those components. The feedingmechanism 16 interfaces with a control computer 62 through a busconversion module 64. In the present embodiment, the conversion module64 converts USB to I²C and back again. Outgoing data from the feedingmechanism 16 is input to the module 64 for conversion to the USB and isthen input to a USB port 66 on the computer 62. Incoming data to controlsoftware 68 may include motor current data and motor encoder data foreach of the motors in the feeding mechanism 16. Joystick data (positiondata) may also be received from a joystick 70. A monitor 72 may beresponsive to video data from a camera mounted on the distal end of theouter sleeve 12 and/or inner core 14 to provide visual feedback to auser regarding the position of the distal end of the HARP 10. Thecontrol software 68 may output motor current limit commands and motorposition commands which are input to the feeding mechanism 16.

FIG. 12 is a block diagram of an exemplary electrical system which maybe used for the feeding mechanism 16. A plurality of PID motorcontrollers 74 are used to control the various linear actuators 46, 48and motors 50, 51, 52, 58. An example of one of the PID motorcontrollers 74 is shown in detail in FIGS. 13A, 13B and 13C. The PIDmotor controller 74 is built around a PIC 18F series microcontroller 95.The motor controller 74 also features a quadrature decoder chip 96, anH-bridge chip 97, and a quad op-amp chip (TLV2374-IPW) having fouramplifiers 98, 99, 100 and 101. The controller 74 also features a numberof discrete components in support of these integrated circuits as wellas three connectors, one connector 103 for the motor, and the other twoconnectors 104, 105 to create a stacking bus structure.

The quadrature chip 96 decodes the two channel encoder data from a motorencoder and outputs up and down clocks which are fed into themicrocontroller 95. The microcontroller 95 uses its counter circuits tocount the forward and reverse movements of the motor shaft to calculatethe current position of the motor shaft.

The H-bridge chip 97 is used to drive the motor. This chip takes a PWMsignal and a direction signal as input from the microcontroller 95 andswitches the motor on and off according to these signals. This chiphandles the higher currents and voltages required by the motor which arebeyond the capabilities of the microcontroller 95 outputs.

The third chip is the quad op-amp. This chip is used entirely for motorcurrent monitoring. One amplifier 98 is used in a non-invertingconfiguration with a gain of 74.2 with its output fed to one of themicrocontroller's 95 analog to digital pins. A second amplifier 99 isconfigured as a non-inverting amplifier with a gain of 500 and is alsoconnected to an analog to digital pin of the microcontroller 95. Thishigher gain gives a more precise current measurement at lower currentvalues. A third amplifier 100 is used to control a current source whichdrives an LED with current proportional to the motor current. This,along with an LED which indicates the direction of motion, gives theoperator a clear visual indication of what the controller 74 is doing.

The microcontroller (PIC) 95 is the heart of this board. This chipfeatures an I²C bus peripheral which is used for communication with thehost computer 62. This is a two way link used to send commands from thecomputer 62 to the controller 74, while status information flows backfrom the controller 74 to the computer 62. The commands from thecomputer 62 are related to position goals and current limits. The statussent back to the computer 62 includes motor electrical currentmeasurements and motor encoder values.

The primary role of the microcontroller 95 is to run a PID positioncontrol loop. The purpose of this PID loop is to minimize the errorbetween the motor encoder count and a dynamically generated positiongoal. This position goal is generated by another component of themicrocontroller program, the trajectory generation system.

The trajectory generation system of controller 74 creates goals based ona final goal supplied over the I²C bus, and a desired time-to-goal valuealso supplied over the I²C bus, as is known in the art. The trajectorygenerator uses these values to create a trapezoidal velocity profile tobring the motor to the desired final position in the specified amount oftime. This working goal is updated at approximately 1 kHz, which is alsothe frequency of the PID loop.

Simultaneously, the microcontroller 95 is also taking readings of themotor current via the on chip analog to digital converter. These valuesare compared against an I²C bus supplied maximum current value, and ifthe measured current exceeds the desired maximum, the PWM output to theH-bridge is throttled back. This also runs at the same frequency as thePID loop.

The controller 74 is designed to allow multiple controllers 74 to bestacked by utilizing a 40 conductor board to board connector 104, 105(FIG. 13B) on both the top and bottom of the board. Because the systemuses the multi-drop I²C bus, only two connections are needed betweenboards in addition to power. The majority of the conductors on thesestacking connectors are used for power to overcome the single pincurrent limitations of small connectors like these.

Motors are connected to their respective controllers 74 through a 2×5100 mil spacing right angle header 103. This is a versatile connectorwhich allows ribbon cable or discrete wiring to the motors. The motorsused on this system were supplied with ribbon cable IDC connectors.

Each board also features 5 LEDs, one of which is shown in FIG. 13A andthe others shown in FIG. 13C, with the others connected to themicrocontroller 95 as shown in FIG. 13A. There is a red LED (closest tothe stacking connector) which is controlled by the motor current. Nextis a yellow LED indicating the sign of the error from the PID loop,which indicates the direction the motor's shaft is being commanded toturn. The middle LED is currently unused and is available for futureuse. The green LED is used as a power/boot indicator and is undersoftware control. Finally, another red LED (near the motor connector) istoggled each time an error is detected on the I²C bus to visuallyindicate bus reliability.

Before the system can be used, the first mechanism 12 and the secondmechanism 14 must be “homed”; that is, their relative positions must bedetermined. This is done by retracting both mechanisms until the linearactuators 46, 48 have reached the end of their range of travel, acondition detected by the system as an increase in actuator current. Thecontrol software 68 uses encoder information to record the positions ofthe first mechanism 12 and second mechanism 14, and homing is complete.

The control software then puts the system in “stepped advancing” modewhich is illustrated in FIG. 14. First, the first mechanism 12 is maderigid at 76. See also FIG. 15A. That is done by driving its tensioningmotor 58 in the direction opposite the tension wire's 59 pull until themotor 58 stalls at its current limit. The second mechanism 14 is madelimp at 78 by driving its tensioning motors 50, 51, 52 in the directionof the tension wires' pull by a fixed number of rotations, so that thewires become slack. The second mechanism 14 is advanced at 80 (See alsoFIG. 15B) so that it is positioned with its distal end one link's lengthbeyond the first mechanism's 12 end. An encoder on the linear actuator46 that is pushing the second mechanism 14 “counts” how far the secondmechanism has moved.

At this point, the software 68 is ready for user input. The software 68monitors the position of the joystick 70 at 82, translating the two-axisdata from the joystick into the three-axis coordinate system of thesecond mechanism 14. The positions of the shafts of the motors 50, 51,52 controlling wires 54, 55, 56, respectively, are varied at 84according to the translated joystick position. Once the user has steeredthe protruding link of the second mechanism 14 to the desired angle, theuser presses a button on the joystick 70 to lock that angle in place asshown at 86. The three tensioning motors 50, 51, 52 are driven in thedirection opposite the tension wires' 54, 55, 56 pull, until theircurrent limits are reached and the motors stall at 88. This begins withthe wire closest to the inside of the angle being formed, progressingafter a small fixed delay to the next wire and finally the wire on theoutermost part of the angle; tensioning the wires in this orderpreserves the user-selected angle more accurately than tensioning themsimultaneously.

Once each of the three motors 50, 51, 52 has reached its current limit,the second mechanism 14 is rigid and the first mechanism 12 can safelybe made limp as shown by 90 by driving its tensioning motor 58 a fixednumber of rotations in the direction of the tension wire's 59 pull. Thefirst mechanism 12 is then advanced by one link's length, so that itsdistal end is even or coextensive with the second mechanism's 14 distalend as shown by 92 and FIG. 15C. An encoder on the linear actuator 48that pushes the first mechanism 12 is used to count how far the firstmechanism 12 advances. Once in this position, the distal links of boththe first mechanism 12 and the second mechanism 14 are at the sameangle. The first mechanism 12 is then made rigid to preserve this angle,and the second mechanism 14 is made limp as shown by 76 and 78. In thisway the process continues, steering the distal link, locking itsposition in place, and advancing in single-link steps until the firstmechanism 12 and second mechanism 14 have been advanced to the desiredlength and path shape.

The description of motion in conjunction with FIG. 14 and FIGS. 15A-15Cassumes that a camera, not shown, is positioned on the distal link ofthe second mechanism 14. Thus, the second mechanism 14 does the steeringwhile the first mechanism 12 simply follows along. The process could ofcourse be reversed with the camera being positioned on the firstmechanism 12 such that the first mechanism 12 does the steering, whilethe second mechanism 14 does the following. In another embodiment,cameras could be provided on the distal ends of both the first mechanism12 and the second mechanism 14 such that the two mechanisms “leap frog”one another. That is, rather than one of the mechanisms merely catchingup with the other, after it is caught up, it can advance by one linkbecause of its capability of being steered. The other mechanism then“catches up” and advances by one link's length because it too has thecapability of steering. It is anticipated that with such a device, adesired position for the end of the HARP 10 may be obtained morequickly.

Although it is anticipated that steering may be achieved through the useof cameras, other mechanisms may be used. For example, the distal linksof each of the first mechanism 12 and second mechanism 14 may becomprised of material which is visible through the use of x-rays, NMRI,or other such devices such that the HARP 10 may be steered by trackingthe advance of the HARP 10 with such a device. Alternatively, a smallamount of radioactive material may be placed on the distal end of eachof the first mechanism 12 and second mechanism 14 such that the progressof the HARP 10 can be tracked. Control of the path and configuration ofthe HARP 10 may be accomplished through the use of intelligentalgorithms. The present invention is not to be limited by the type ofmechanism used to provide information for steering and/or guidance ofthe HARP 10.

The process of retracting the mechanisms takes place in the same way asadvancing does, but in reverse order, and without steering input fromthe user as shown in FIG. 16. Once the user has selected “Retracting”mode using the joystick 70, the second mechanism 14 is retracted so thatits distal end is even with the distal end of the first mechanism 12.The second mechanism 14 is made rigid, and the first mechanism 12 ismade limp. Then the first mechanism 12 is retracted by one link'slength, and the first mechanism 12 is made rigid. The second mechanism14 is made limp, and again retracted until the distal end of the secondmechanism is even with the distal end of the first mechanism 12. Thatcycle continues until the user presses a button to stop it, or until thefirst mechanism 12 and second mechanism 14 reach their home positions.

Turning now to experimental results, an off-the-shelf fiber optic basedcamera and video camera, such as the Olympus PF14 insertion tube 1.4 mmwas introduced through the open central portion of the links of an innercore 12 designed to have a 6 mm diameter opening. Another option wouldbe to integrate the video camera into the walls of the links of theouter sleeve 14, which are currently 3 mm thick. With such a device, andas shown in FIGS. 18 and 19, we were able to navigate the pericardialspace of a porcine.

The normal pericardium is a double-layered, flask-shaped sac consistingof an outer fibrous envelope and in inner serous sac that is invaginatedby the heart. The pericardial cavity or sac is a continuous virtualspace that lies between the two opposite layers of serous pericardium.At the pericardial reflections and at the posterior wall between thegreat vessels, the pericardial space is apportioned into a contiguousnetwork of recesses and sinuses; all pericardial reflections are locatedbasally in relation to the great vessels. Thus, there are no obstaclesduring intrapericardial navigation along the anterior ventricularsurface of the heart. There are three sinuses in the pericardial space:the superior sinus (also referred to as superior aortic recess), thetransverse sinus contains several recesses between the major vessels(superior aortic, inferior aortic, right pulmonary and left pulmonaryrecess). The inferior aortic recess allows access to the epicardialaspect of the noncoronary and right coronary aortic cusps. The obliquesinus extends behind the atria, particularly the left atrium, in theregion between the four pulmonary veins. There are five recesses of thepericardial cavity: superior aortic (SAR), inferior aortic (AR),postcaval (PCR), left pulmonary (LPVR) and right pulmonary (RPVR).

As shown in FIGS. 18 and 19, we were able to explore the oblique sinusand visualize the posterior atrium, explore the transverse sinus withentry from the right and from the left with visualization of the leftatrial appendage and explore all five recesses (SAR, IAR, PCR, LPVR andRPVR). Thus, the device and method of the present invention allow forvarious types of endoscopy or visualization of internal organs (orparts) or intracavity spaces from an on-board camera (or lens and lightpipe) mounted on an articulated probe. It is the real time imagesprovided by the on-board camera that allow teleoperation, i.e. remotecontrolled, 3D guidance in real time.

While the present invention has been described in connection withpreferred embodiments thereof, those of ordinary skill in the art willrecognize that many modifications, variations and substitutions arepossible. For example, as shown in FIG. 20, the first mechanism 12 andthe second mechanism 14 are shown in a spaced relationship, i.e. not onewithin the other. In such an embodiment, one or both of the mechanismsmay have members for maintaining the spaced relationship as the device10 moves. Accordingly, the present invention is not intended to belimited by the disclosed embodiments but rather is limited only by thescope of the following claims.

What is claimed is:
 1. An articulated probe, comprising: a firstmechanism comprised of a plurality of links; a second mechanismcomprised of a plurality of links; a first wire extending through eithersaid plurality of links of said first mechanism or said plurality oflinks of said second mechanism and a plurality of wires running throughthe other of said plurality of links of said first mechanism or saidplurality of links of said second mechanism; a device for producingcommand signals; and an electromechanical feeder responsive to saidcommand signals, said electromechanical feeder comprising: a firstlinearly movable cart, one of said first mechanism or said secondmechanism being responsive to said first cart; a second linearlymoveable cart, the other of said first mechanism or said secondmechanism being responsive to said second cart; wherein said first cartcan be advanced when said first mechanism being responsive to said firstcart is in a limp state and said second mechanism being responsive tosaid second cart is in a rigid state; a first actuator for controllingthe position of said first cart; a second actuator for controlling theposition of said second cart; a first tension mechanism for controllingthe tension of said first wire, said first tension mechanism carried bysaid first cart; and a plurality of tension mechanisms for controllingthe tension of said plurality of wires, said plurality of tensionmechanisms carried by said second cart, wherein each tension mechanismcontrols the tension of one of the wires, wherein said first tensionmechanism, said plurality of tension mechanisms, said first actuator andsaid second actuator each comprises a motor.
 2. The probe of claim 1wherein said links are selected from a group consisting of dogbone andbackbone shaped links.
 3. The probe of claim 1 wherein said firstmechanism is located along side said second mechanism, one of said firstand second mechanisms including members for maintaining a spacedrelationship between said first and said second mechanisms.
 4. The probeof claim 1 wherein said first mechanism is located inside said secondmechanism.
 5. The probe of claim 1 wherein said device for producingcommand signals produces command signals to cause one of the first andsecond mechanisms to be limp while the other of said mechanisms is rigidto enable the limp mechanism to be advanced using said rigid mechanismas a guide thereby preserving the probe's configuration.
 6. The probe ofclaim 1 additionally comprising: a plurality of shaft encoders, each ofsaid first tension mechanism and said plurality of tension mechanismsbeing responsive to one of said plurality of shaft encoders.
 7. Theprobe of claim 1 wherein said device for producing command signalsproduces command signals referenced to a homed position.
 8. The probe ofclaim 1 wherein said probe has a range of motion of 14°.
 9. The probe ofclaim 1 wherein one of said first mechanism or said second mechanismcarries a camera on a distal end thereof.
 10. The probe of claim 1wherein each of said first mechanism and said second mechanism carries acamera on a distal end thereof, and wherein each of said first mechanismand said second mechanism are steerable.
 11. The probe of claim 1wherein said links are cylindrical.